The iBiquity Digital Corporation HD Radio™ system is designed to permit a smooth evolution from current analog Amplitude Modulation (AM) and Frequency Modulation (FM) radio to a fully digital In-Band On-Channel (IBOC) system. This system delivers digital audio and data services to mobile, portable, and fixed receivers from terrestrial transmitters in the existing Medium Frequency (MF) and Very High Frequency (VHF) radio bands. Broadcasters may continue to transmit analog AM and FM simultaneously with the new, higher-quality, and more robust digital signals, allowing themselves and their listeners to convert from analog to digital radio while maintaining their current frequency allocations.
The HD Radio system allows multiple services to share the broadcast capacity of a single station. One feature of digital transmission systems is the inherent ability to simultaneously transmit both digitized audio and data. Thus the technology also allows for wireless data services from AM and FM radio stations. First generation (core) services include a Main Program Service (MPS) and the Station Information Service (SIS). Second generation services, referred to as Advanced Application Services (AAS), include new information services providing, for example, multicast programming, electronic program guides, navigation maps, traffic information, multimedia programming and other content.
The HD Radio system provides a platform for the delivery of a wide range of services, both audio and data. For efficient transmission and reception of these services, it would be desirable to have a single information transfer protocol that could be used to transfer information between diverse components in an HD Radio broadcasting system.